1. Technical Field
This invention relates to constant velocity universal joints.
2. Related Art
Constant velocity joints are used to transmit torque through an angle while maintaining constant velocity ratio between a driving and driven shaft member of the joint at all angles. A typical constant velocity joint includes an outer joint member formed with a part-spherical inner surface and a series of ball grooves, an inner joint member formed with a part-spherical outer surface and a series of complimenting ball grooves aligned with the grooves of the outer joint member, a plurality of torque-transmitting balls received in the aligned grooves, and a ball cage disposed between the inner and outer joint members and having part-spherical surfaces in contact with those of the inner and outer joint members for articulation of the joint and capture of the balls within the grooves.
The package size of a constant velocity joint is dependent in part on the angle to be achieved in the stack-up dimensions of the component parts, namely the inner joint part, the outer joint part and the intervening ball cage. Reducing the thickness of any one or more of these components may impair the strength or integrity of the joint, and thus there is a limit as to how small the conventional constant velocity joint can be made without detracting from its strength or reducing its degree of articulation.
U.S. Pat. Nos. 5,201,107 and 5,230,659 disclose constant velocity joints in which the conventional cage has been eliminated and the balls held in the grooves by a retainer within the outer joint member. Both joints are of rather complex construction, requiring special machining and component parts as well as special installation techniques to assemble the parts. The ball retainer of U.S. Pat. No. 5,201,107 is pivotally supported by the outer joint member along a line of curvature corresponding to that of the contact surfaces between the inner and outer joint members, which lends to a rather large package size in both the radial and axial directions.
It is an object of the present invention to provide a simple, efficient, compact constant velocity joint.
A constant velocity joint assembly constructed according to the invention comprises an outer joint member and an inner joint member disposed at least partially within the outer joint member. The outer and inner joint members have abutting contact surfaces supporting the joint members for relative pivotal movement about a fixed center point of the joint members. The outer and inner joint members have a plurality of circumferentially spaced ball grooves formed in the contact surfaces and diverging toward one end of the outer joint member. A plurality of torque-transmitting balls are disposed in the ball grooves. A ball retainer is disposed within the outer joint member and has an inner seat portion and a ball-engaging portion engaging the balls. The inner joint member has an end portion engaging the inner seat portion of the ball retainer and supporting the ball retainer for relative pivotal movement about a pivot point common with the fixed center point of the outer and inner joint members.
The invention has the advantage of simplifying the construction and assembly of fixed-center constant velocity joints. The ball retainer is constructed and supported in such manner as to provide an overall compact constant velocity joint in length and in diameter compare to known prior art constant velocity joints with and without the usual ball cage.
The invention has the further advantage of providing an inner joint member which is solid throughout in the vicinity of the center of the joint and which directly supports the ball retainer during pivotal movement, providing strength and integrity to the joint under load.